1. Field of the Invention
The present invention relates generally to a storage apparatus and its cooling method, and more specifically to a storage apparatus in which hard disk drives are housed in a generally-used housing from two sides of the housing, and a cooling method for such a storage apparatus.
2. Description of Related Art
A system handling data on a large scale, as one provided in a data center or similar, manages data using a host computer and a storage apparatus. The storage apparatus includes hard disk drives arranged in an array and protects data using a RAID system.
In relation to the increase of an amount of data handled in a storage apparatus, the number of hard disk drives installed in the storage apparatus is increasing. For example, JP2008-47249 discloses a storage apparatus having a housing dedicated to housing a large number of hard disk drives.
This type of storage apparatus has cooled the hard disk drives by supplying air to the housing from a surface of the housing and having the air flow in a flow path formed in the housing, and then expelling the air from a top surface of the housing.
On the other hand, there is also a storage apparatus that does not have a dedicated housing, but instead has a generally-used rack that enables a user to add, as needed, modules having hard disk drives to the rack (see, JP2007-11931 A).
This type of storage apparatus cannot be provided with an exhaust fan on a top surface of the rack, and in addition, cannot be provided with an airflow path in the rack, so it has had a structure in which a module including a power source and a fan integrally in the hard disk drive is housed in the rack.
The module is inserted in the rack in such a manner that the hard disk drive is located on a front side of the rack. The air is introduced from a front side of the module into the rack and expelled from a rear side of the module.
Also in the storage apparatus using the housing with the generally-used rack, the number of hard disk drives mounted in the housing increases as the amount of handled data increases. In order to increase the mount density of hard disk drives when the hard disk drives are stacked up in the housing, the size of the housing needs to be increased so that it can house a higher stack of the hard disk drives.
In light of the above circumstances, a more preferable type would be those allowing the hard disk drives to be inserted from both the front and rear sides of the housing to increase the mount density of the hard disk drives.
It is difficult to mount conventional modules in the housing from both the front and rear sides of the housing, since the size of the modules is too great. A possible solution for this problem would be to provide a fan at least on one of both the front and rear sides of the housing, instead of incorporating the fan in the modules, and to cool the hard disk drives that have been mounted in the housing from both the front and rear sides of the housing.
However, if the fan is provided on the front side in the housing, the fan will be an obstacle to maintenance and replacement of the hard disk drive(s) in the housing.
Also, because air with an increased temperature after passing through the hard disk drives located on the front side in the housing passes through the hard disk drives located on the rear side in the housing, cooling performance for the hard disk drives on the rear side in the housing is insufficient.
In view of the foregoing, in the storage apparatus employing the generally-used housing, hard disk drives have not been mounted from both the front and rear sides of the housing.
It is an object of the present invention to provide a storage apparatus that houses storage devices in a housing by mounting them in the housing from both front and rear sides of the housing and that enables maintenance and replacement of the storage device(s) even if a cooling device is provided at a position facing the storage devices.
It is another object of this invention to provide a storage apparatus having an excellent cooing performance for storage devices that are mounted in a housing from both the front and rear sides of the housing.
It is another object of this invention is to provide a cooling method for efficiently cooling the storage apparatus that houses, in a housing, storage devices mounted from both the front and rear sides of the housing.